On Mon, 27 Nov 2017, Brian Gerst wrote:> On Mon, Nov 27, 2017 at 6:47 AM, Thomas Gleixner <tglx@linutronix.de> wrote:> > On Mon, 27 Nov 2017, Peter Zijlstra wrote:> >> On Mon, Nov 27, 2017 at 12:14:04AM +0100, Thomas Gleixner wrote:> >> > PAGE_NX and PAGE_GLOBAL might be not supported or disabled on the command> >> > line, but KAISER sets them unconditionally.> >>> >> So KAISER is x86_64 only, right? AFAIK there is no x86_64 without NX> >> support. So would it not make sense to mandate NX for KAISER?, that is> >> instead of making "noexec" + KAISER work, make "noexec" kill KAISER +> >> emit a warning.> >> > OTOH, disabling NX is a simple way to verify that DEBUG_WX works correctly> > also on the shadow maps.> >> > But surely we can drop the PAGE_GLOBAL thing, as all 64bit systems have it.> > I seem to recall that some virtualized environments (maybe Xen?) don't> support global pages.

Uuurg. Ok, we leave it as is for now. Better safe than sorry. It does noharm.